Height comparator

ABSTRACT

A device is provided for measuring the centre of a grinding wheel for use in setting the height of a skate blade. The device has a base, a support extending from the base, a slider block slidable along the neck between the base and a head block secured to an upper end of the neck, a dial indicator supported by the head block for measuring the position of the slider block along the neck, a lower roller, and an upper roller. The lower roller and upper roller are rotatably attached to the slider block and radially aligned with each other such that a portion of each roller protrudes from the slider block, wherein a clockwise tangential force imparted on the upper roller causes the slider block to slide along the neck, and the dial indicator to record the movement of the slider block, which enables the height of an object to be set on the dial indicator with respect to a rest position of the slider block.

This application claims priority from U.S. Provisional Patent Application No. 60/667,689 filed Apr. 4, 2005.

FIELD OF THE INVENTION

The present invention relates to devices for measuring, comparing, and setting the height of an object and has particular utility in centring the hollow of a skate blade with respect to the grinding wheel of a skate sharpener.

DESCRIPTION OF THE PRIOR ART

The blade of an ice skate comprises a concave lower surface, providing a pair of edges at terminal ends of the concave surface. This concave surface is generally referred to as the “hollow” of the blade. To maintain the hollow, and thus the pair of edges, the skate is periodically sharpened using a skate sharpening machine.

A typical skate sharpening machine is generally comprised of a table-top or working surface, and a motor driven grinding wheel mounted on the surface. In order to restore a blade's hollow, the grinding wheel is oriented substantially parallel to the working surface. Before the grinding wheel is used for sharpening skates, typically it is first “dressed”. Dressing the wheel involves creating a desired convex surface about the periphery of the grinding wheel, which matches the desired hollow of the blade. Once the wheel has been dressed, the skate blade may then be sharpened.

The technique used for creating and/or restoring a hollow is typically referred to as finish grinding. Finish grinding involves bringing the blade towards the grinding wheel, as it rotates, through a path which is parallel to and aligned with the tangential direction of the rotating grinding wheel. When the blade contacts the rotating grinding wheel, the wheel's abrasiveness effectively grinds the hollow to its desired concavity, i.e., to match the convexity of the periphery of the grinding wheel.

It is important for the skate blade to have an even edge (i.e. where the terminal edges of the concave surface intersect a common diameter of the hollow). To ensure an even edge, care should be taken to accurately centre the skate blade with respect to the grinding wheel. The effect of centring the skate blade vertically aligns the length of the blade with the edge of the grinding wheel, enabling an even transfer of curvature from the grinding wheel to the blade. To assist in finish grinding, the ice skate is preferably held in place using a clamping device, known as a skate holder. The skate holder is free to move atop the working surface, and orients the skate blade in the above described position relative to the grinding wheel.

Many available skate holders permit an operator to adjust the height of the skate blade using a suitable levelling mechanism, enabling the blade to be centred with respect to the grinding wheel. However, this requires that the operator place the skate blade against the grinding wheel (while stopped) and adjust the height of the skate holder until the operator is satisfied that the blade has been adequately centred. Such an operation can be awkward and inaccurate due to the size of the skate sharpening machine and the angle at which the operator would observe the alignment of the blade with respect to the grinding wheel.

Moreover, if the operator is required to sharpen a number of skates in succession, they would need to perform the above technique for each skate, to ensure that they are satisfied that each skate blade is properly centred before it is sharpened. The downtime between successive sharpenings to center each skate blade, can hinder the productivity of the operator.

Performing such a technique in the vicinity of the grinding wheel also poses the risk of the grinding wheel inadvertently powering on without warning, creating a hazard for the operator.

It is therefore an object of the present invention to provide a device that obviates or mitigates at least one of the above-described disadvantages.

SUMMARY OF THE INVENTION

A device for measuring the height of one object for use in setting the height of another object is provided. The device comprises a base, a support extending from the base, a measuring head displaceable relative to the support within a defined range, an indicator for measuring the position of the measuring head relative to the support, and a centering guide engageable with the one object and the another object, wherein the centering guide moves the measuring head relative to the support while locating the height of the one object, and the indicator is operable to capture the height of the one object for use in setting the height of the another object.

As a preference, a magnetic lock is housed in the base for actuating a magnetic force between the base and a working surface on which the base rests.

As another preference, a stop collar is included which slides over the support and can be secured thereto for setting a lower limit for the position of the measuring head.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will now be described by way of example only with reference to the appended drawings wherein:

FIG. 1 is a perspective view of a skate sharpening environment.

FIG. 2 is a perspective view of an embodiment of a height comparator.

FIG. 3 is an exploded view of the embodiment of FIG. 2.

FIG. 4 is an elevation view of the embodiment of FIG. 2.

FIG. 5 is a perspective view of the embodiment of FIG. 2 in use.

FIG. 6 is another perspective view of the embodiment of FIG. 2 in use.

FIG. 7 is a pair of perspective views of another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Referring therefore to FIG. 1, a typical skate sharpening environment is shown. A table has a working surface 12 that supports a skate sharpening machine 80. The working surface 12 is preferably made of a material that is attracted to a magnet. The machine 80 is mounted on the surface 12, and a portion of a grinding wheel 82 protrudes through a slot 84 formed in a shield 86. The surface 12 also supports a clamping-type skate holder 90. The holder 90 has a base 92 that rests on the surface 12. The base 92 supports a levelling plate 94 with a pair of levelling mechanisms 100 (one of them is not shown) having adjustment handles 102. A skate 200, having a blade 202, is clamped between the plate 94 and a jaw 97. The jaw 97 is part of a clamping mechanism 96, and is operated by pivoting a handle 98, which is also part of the clamping mechanism 96. A device for measuring the height of an object to be used in setting the height of another object is also supported on the surface 12 and is generally denoted by numeral 10.

The device 10 is shown in greater detail in FIGS. 2-4. The device 10 has a base 14, which rests on the surface 12. The base 14, in this embodiment, is a cylindrical block, which contains a magnetic clamp 18 operated by a switch 16. The clamp 18 fits into a slot 65, and upon operating the switch 16, the base 14 becomes attracted to the surface 12. The clamp 18 is a well known component in the art. The base 14 also has a vertically oriented bore 66, for receiving a support, in this example dowel 20; and a threaded, horizontally oriented bore 22, for receiving a set screw 22. The set screw 22 is used to engage the dowel 20 and secure it to the base 14.

A stop collar 26, is sized to slide over the dowel 20. The collar 26 has a threaded bore 64 to receive a set screw 28 for engaging the dowel 20, and to hold the collar 26 at a desired position along the dowel 20. A measuring head, in this example slide block 30, has a vertically oriented bore 58, sized to receive the dowel 20, enabling the block 30 to slide along the dowel 20 and rest upon the collar 26. The block 30 has a horizontal channel 39, and vertical slot 41.

The channel 39 is flanked by an upper bore 60, and a lower bore 62. The bores 60 and 62 pass through the slot 41 and the width of the block 30. An upper roller 36 is supported within the slot 41 by an upper dowel pin 35; and a lower roller 38 is supported within the slot 41, below the upper roller 36, by a lower dowel pin 37. The dowel pins 35 and 37 are sized to frictionally engage the walls of the upper and lower bores 60 and 62 respectively, in order to hold the rollers 36 and 38 in place. As best shown in FIG. 3, a portion of each of the rollers 36 and 38 partially protrudes into the channel 39, and a portion of each protrudes to the exterior of the block 30 to define convergent surfaces that centre the block on the wheel 82.

A head block 32 has a first vertically oriented bore 52, a second vertically oriented bore 50, a first horizontally oriented bore 54, and a second horizontally oriented bore 56. The bore 52 is sized similar to the bore 58, enabling the block 32 to slide over the dowel 20. The bores 54 and 56 are threaded, and sized similar to the bore 22, such that they may receive set screws 42 and 40 respectively. The set screw 42 engages the dowel 20 to secure the block 32 at a desired position. The bore 50 is sized to receive a stem 44 that extends from a dial indicator 34. The set screw 40 engages the stem 40 to secure the dial indicator 34 atop the block 32.

The dial indicator 34 has a rotatable face 46. The rotatable face 46 has a set of markings 47 about its circumference, enabling a desired one of the markings 47 to be aligned with a needle 48. As shown in FIG. 4, the stem 44 partially protrudes beyond the lower surface of the head block 32 and is moveable towards the dial indicator 34 when it is pushed from below. The stem 44 is connected to the needle 48, such that movement of the stem 44 produces a corresponding movement of the needle 48.

In order to enable the device 10 to measure the height of an object, the collar 26 should be secured at a particular position, depending on that height. The slide block 30, and thus the rollers 36 and 38 are intended to have a certain range of travel along the dowel 20, wherein the typical height of the object being measured should fall within the range of travel of the rollers 36 and 38. The collar 26 is thus secured to the dowel 20 at a height suitable to inhibit downward movement of the block 30 beyond the lowermost point in its desired range of travel.

The position of the head block 32 should place the lower surface of the block 32 at the upper limit of the desired range of travel of the block 30. In this position, the block 32 allows upward movement of the block 30 until the block 30 reaches the upper limit of its range of travel. The stem 44 has a sufficient range of movement to accommodate the movement of the block 32 within the range of travel so that movement of the block 30 will cause a corresponding movement of the needle 48 of the dial indicator 34.

The following describes how the device 10 can be used for setting the height of a skate blade for the purpose of sharpening the skate blade, making reference to FIGS. 5 and 6.

The device 10 is first used to measure the “centred” height of the dress of the grinding wheel 82. Thus, in this example, it will be assumed that the grinding wheel 82 has already been dressed, and is ready to be used to perform a finish grind on a skate blade.

The range of travel of the block 30, described above, would be chosen according to the height of the grinding wheel 82 with respect to the surface 12. A suitable height for the grinding wheel 82 is about 4½″. Since the collar 26 has been secured to the dowel 20 such that the block 30 rests at the lower end of its range of travel, the lower roller 38 would lie below the grinding wheel 82 when the device 10 is not in use. At this point, the needle 48 would be at its rest position.

To measure the centre of the dress on the grinding wheel 82, the device 12 is brought towards the grinding wheel 82, wherein the upper roller 36 would contact the grinding wheel 82 first. The device 10 would then be pushed further towards the grinding wheel 82, exerting a substantially tangential force on the upper roller 36. This force would cause the upper roller to move along the curvature of the grinding wheel 82 which in turn causes the block 30 to slide up along the dowel 20 until the lower roller 38 is also in contact with the grinding wheel 82. The position of the rollers 36 and 38 at this point indicates the center of the dress on the grinding wheel 82. The upward movement of the block 30, moves the stem 44, which in turn rotates the needle 48 a distance that corresponds to the extent to which the stem 44 has moved.

The face 46 is then rotated to align a “zero” on its dial markings 47 with the position of the needle 38. This zero marking indicates the required position of the needle 48 (and thus the required position of the slider block 30) to replicate the centre of the wheel 82.

The device 10 may then be moved away from the machine 80, along the surface 12, to an unobtrusive location. Preferably, the device 10 is then firmly locked to the surface 12 by turning the switch 16, which causes the base 14 to be magnetically attracted to the surface 12.

To set the height of the blade 202, the skate holder 90 having the skate 200 clamped therein, is brought to the device 10, and the levelling mechanisms 100 are adjusted to place the height of the blade 202 substantially level with the channel 39. At this point, the skate holder 90 should remain seated on the surface 12 and the blade 202 should be touching at least one of the rollers 36 and 38.

The levelling mechanisms 100 can then be used to raise or lower the blade 202. As the blade 202 is raised, it should be held against the rollers 36 and 38 and maintain contact with at least the upper roller 36. This will cause the block 30 to slide along the dowel 20 in an upward direction, plunge the stein 44, and move the needle 48. The blade 202 should be raised until the needle 48 points to the zero marking on the dial 47, which was previously set when measuring the height of the grinding wheel 82. Once this height has been achieved, the blade 202 is now centred. Typically, this operation is performed at each end of the blade 202 to level the blade 202 as well as to adjust its height in order to ensure that the entire length of the blade 202 is centred.

The skate blade 202 may then be given a finish grind using the grinding wheel 82, with confidence that the skate blade 202 has been accurately centred, resulting in an even hollow.

Subsequent skates that are clamped in the holder 90, can be centred using the device 10, which is preferably positioned a safe distance from the machine 80. This can be repeated for each skate 200 that is sharpened, until the grinding wheel 82 is dressed again. This ensures that each time the skate holder 90 is used, its height is accurately set so that the blade 202 receives an even hollow. The skate holder 90 may vary in height since different skate blades 202 can have a different thickness and, moreover, there is no guarantee without measuring that the skate holder 90 has not been readjusted between successive skate sharpening operations.

In another embodiment shown in FIG. 7, a dial lock device 300 is used. A bottom portion 301 of the dial indicator 34 includes a bore 305 that is adapted for receiving a threaded rod 303. The threaded rod 303 extends from a collar 302 which has a thumbscrew 304 at its other end. The rod 303 is first threaded through a foot 306 until its shoulder engages the foot 306 and is then threaded into the bore 305. The thumbscrew 304 may be turned by hand to advance the foot 306 along the rod 303 until it presses against the rotatable face 46. The thumbscrew 304 may then be turned in an opposite manner to release the foot 306. The lock device 300 may be used to lock the face 46 after it has been set to zero during the procedure explained above. The purpose of locking the face 46 in position is to inhibit accidental movements of the face 46 once it has been set, which can lead to inaccurate height settings.

Therefore, the device 10 provides a safe, quick, stable, and effective way to center the height of a skate blade 202, without requiring the operator to adjust the skate holder 90 with respect to the grinding wheel 82 each time a new skate 200 is sharpened, which can be inaccurate and/or dangerous. The device 10 also promotes an efficient skate sharpening routine, since the device 10 can quickly and accurately center successive skate blades 202 without requiring the machine 80 to be turned off causing unnecessary down time.

Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto. 

1. A device for measuring the height of one object for use in setting the height of another object, said device comprising a base, a support extending from said base, a measuring head displaceable relative to said support within a defined range, an indicator for measuring the position of said measuring head relative to said support, and a centering guide engageable with said one object and said another object, wherein said centering guide moves said measuring head relative to said support while locating the height of said one object, and said indicator is operable to capture the height of said one object for use in setting the height of said another object.
 2. A device according to claim 1 wherein said base includes a locking mechanism for securing said base to a surface.
 3. A device according to claim 1 wherein said locking mechanism is a magnetic switch which may be activated to generate a magnetic attraction between said base and said surface.
 4. A device according to claim 1 wherein said measuring head is slidable relative to said support.
 5. A device according to claim 4 further comprising a stop collar engageable with said support for setting a lower limit of travel for said measuring head along said support.
 6. A device according to claim 5 wherein said stop collar engages said support using a setscrew.
 7. A device according to claim 1 wherein said indicator comprises a dial and a needle for indicating said height.
 8. A device according to claim 7 wherein said dial includes a rotatable face, said rotatable face comprising at least one marking for indicating said height, said at least one marking including a zero marking for aligning with said needle to capture said height.
 9. A device according to claim 8 further comprising a dial lock for securing said rotatable face subsequent to capturing said height.
 10. A device according to claim 1 wherein said centering guide includes a pair of convergent faces to centre said measuring head relative to said one object.
 11. A device according to claim 10 wherein said faces comprise curved surfaces.
 12. A device according to claim 11 wherein said curved surfaces are provided by a pair of rollers being rotatable about respective axes.
 13. A device according to claim 12 wherein said rollers are supported by said measuring head and include a channel therebetween to permit passage of a portion of one of said one object and said another object during measurement.
 14. A device according to claim 1 wherein said one object is a grinding wheel and said another object is a skate blade. 